The purpose of this project was to extend existing human movement analysis methodology by developing an analytical technique (induced acceleration analysis) that can provide direct estimates of the influence of muscular effort on the movement of all joints and body segments, and overall functional movement task performance. Applying the technique to data from a group of normal walkers clearly indicated that the muscles that cross the ankle joint are the primary contributors to normal walking performance. Clinical case studies involving patients with physical impairments have revealed a vast array of compensatory movement control strategies. The ability to accurately predict the effects of disease and treatment on an individuals ability to function relies entirely on our capacity to understand the complex process that transforms muscular effort into functional movements. The induced acceleration analysis technique is the first of its kind capable of relating muscular effort to the control of com-plex functional movement tasks. This capability adds significantly to the foundation on which our ability to ultimately understand the influence of disease on function and pre-dict the onset of disability will rest.